could obstruct
Regular verb: obstruct - obstructed- obstructed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could obstruct
you could obstruct
she could obstruct
we could obstruct
you could obstruct
they could obstruct 	I could be obstructing
you could be obstructing
she could be obstructing
we could be obstructing
you could be obstructing
they could be obstructing	I could have obstructed
you could have obstructed
she could have obstructed
we could have obstructed
you could have obstructed
they could have obstructed	I could have been obstructing
you could have been obstructing
she could have been obstructing
we could have been obstructing
you could have been obstructing
they could have been obstructing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not obstruct
you could not obstruct
she could not obstruct
we could not obstruct
you could not obstruct
they could not obstruct 	I could not be obstructing
you could not be obstructing
she could not be obstructing
we could not be obstructing
you could not be obstructing
they could not be obstructing	I could not have obstructed
you could not have obstructed
she could not have obstructed
we could not have obstructed
you could not have obstructed
they could not have obstructed	I could not have been obstructing
you could not have been obstructing
she could not have been obstructing
we could not have been obstructing
you could not have been obstructing
they could not have been obstructing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I obstruct?
could you obstruct?
could she obstruct?
could we obstruct?
could you obstruct?
could they obstruct? 	could I be obstructing?
could you be obstructing?
could she be obstructing?
could we be obstructing?
could you be obstructing?
could they be obstructing? 	could I have obstructed?
could you have obstructed?
could she have obstructed?
could we have obstructed?
could you have obstructed?
could they have obstructed? 	could I have been obstructing?
could you have been obstructing?
could she have been obstructing?
could we have been obstructing?
could you have been obstructing?
could they have been obstructing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not obstruct?
could you not obstruct?
could she not obstruct?
could we not obstruct?
could you not obstruct?
could they not obstruct? 	could I not be obstructing?
could you not be obstructing?
could she not be obstructing?
could we not be obstructing?
could you not be obstructing?
could they not be obstructing? 	could I not have obstructed?
could you not have obstructed?
could she not have obstructed?
could we not have obstructed?
could you not have obstructed?
could they not have obstructed? 	could I not have been obstructing?
could you not have been obstructing?
could she not have been obstructing?
could we not have been obstructing?
could you not have been obstructing?
could they not have been obstructing?